This invention relates to the measuring of the amplitude of oscillation of a balance of a timepiece movement and, more particularly, to a method of and apparatus for linearly measuring this amplitude by using digital techniques.
In evaluating the operation of timepiece movements, such as watch movements, or the like, it is desirable to measure the amplitude of oscillation of the balance. When timepiece movements of a relatively small size are to be evaluated, it often is difficult to attain accurate measurements of such an amplitude of oscillation. Many of the techniques which presently are used for this measurement are complex and expensive. For example, one such technique relies upon the use of a graduated cathode ray tube. In use, the electron beam scans the graduations during cathode ray tube. In use, the electron beam scans the graduations during each swing, or alternation, of the watch movement. A skilled technician must be capable of tracking this moving beam and evaluating the cathode ray tube display.
In accordance with another technique, a conventional moving-coil type of instrument is used. The information displayed by this instrument also requires particular skills of a technician in order to evaluate the performance of the measured watch movement.
In addition to the foregoing techniques, analog electrical measuring apparatus have been used to measure the relationship between various watch movement parameters to thereby derive an indication of the amplitude of oscillation of the balance. In general, the swing of the balance between disengagement and engagement in both the forward and return directions of the balance occurs in a period of time .DELTA. T which can be measured. Also, for a given watch movement, the angle of lift .tau. and the rate of the balance wheel likewise can be obtained. These parameters are related in accordance with the following mathematical representation: ##EQU1## This equation can be electronically simulated by the use of relatively simple analog circuits. However, in order to avoid a complex and, consequently, costly system, the analog implementation of this equation results in a non-linear measurement of the amplitude of oscillation A. This, in turn, results in a lack of precision in the measurement.